COLUMBUS, Ohio - Two months ago, at what was at the time a 6-0 season for the Ohio State football team, we handed out midterm grades for the Buckeyes' defensive position groups. With six more games- all OSU victories- now in the books, here's a look at the final grades that we've assessed to the Buckeyes' defense at the end of their 12-0 perfect season.

Defensive line

Midterm grade: B

Final grade: A-

The Buckeyes' defensive line was considered a bit of a disappointment in Ohio State's first half of the season, failing to create constant pressure on opposing quarterbacks.

That all changed in the second half of the season, when John Simon emerged as the Big Ten's leader in sacks with nine, en route to being named the conference's Defensive Player of the Year. Also a first-team All-Big Ten selection and the league's Defensive Lineman of the Year, the senior defensive end capped off a career that will see him leave Ohio State as the school's No. 7 leader in both sacks and tackles for a loss.

Simon didn't do it all on his own, however, with Johnathan Hankins providing constant pressure up the middle, despite seeing his numbers slip from his sophomore season. The 322-pound nose tackle will now decide whether to return to school for his senior year or enter the 2013 NFL Draft, where he is projected to be a first round pick.

A year after undergoing microfracture knee surgery, Nathan Williams returned to full strength in the second half of the season, tallying 40 tackles and two sacks. Nose guard Garrett Goebel was also solid, recording 42 tackles, four of which came for a loss.

A couple of up-and-coming Buckeyes defensive linemen also showed promise in the second half of the year, with Noah Spence and Adolphus Washington earning more playing time in the latter part of the season. Both true freshmen will likely find themselves as anchors of the unit in 2013, which could be replacing four starters in Hankins does go pro.

Linebackers

Midterm grade: C

Final grade: B

Right after our midterm grades were posted back in October, the Buckeyes' linebackers got a much needed boost in the form of fullback Zach Boren. After spending the first 3 and a half years of his college career trying to block for ball carriers, Boren opted to try to bring them down, converting to linebacker prior to the Buckeyes' Oct. 13 win over Indiana. And while there was a slight adjustment period for Boren, he still finished as Ohio State's sixth-leading tackler, despite spending just half of the season on defense.

Sophomore Ryan Shazier also picked up his play, earning a pair of Big Ten Defensive Player of the Week awards en route to finishing third in the conference- and first on the Buckeyes- with 115 tackles. A first-team All-Big Ten selection, Shazier appears poised to become Ohio State's next great linebacker in his junior year.

After fracturing his fibula against Nebraska, Etienne Sabino returned for the Buckeyes' final two games of the season, capping off a senior season that saw him finish seventh on the team in tackles with 45.

Depth still remained an issue for the Buckeyes' backers throughout the season, with Boren's switch happening in large part because OSU coach Urban Meyer was reluctant to play true freshmen like Joshua Perry and Camren Williams on a consistent basis. The Buckeyes will need those players to step up in 2013 with Boren, Sabino, and Storm Klein all out of eligibility.

Defensive backs

Midterm grade: A-

Final grade: B+

It's hard to get too down on a unit that saw neither of its two starting cornerbacks give up a touchdown reception all season.

Much of that had to do with the stellar play of third-year sophomore Bradley Roby, who broke up 17 passes and recorded two interceptions in 2012. His partner-in-crime, Travis Howard, wasn't as special, but was certainly solid, earning first-team All-Big Ten honors after breaking up six passes and intercepting four balls.

Behind Roby and Howard, Christian Bryant and C.J. Barnett weren't as spectacular as their secondary running mates, but were good enough help shore up a defensive unit that gave up way too many big plays in the first half of the year. The coaches would probably like for Bryant to be a little less aggressive and get more consistency out of Barnett, but both ranked in the Buckeyes' top-four tacklers, and are expected to be back for their senior seasons in 2013.